What’s Vulnerable › Vulnerabilities

CVE-2026-39407: Hono has a middleware bypass via repeated slashes in serveStatic

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-08 · updated 2026-07-24
• Weakness: CWE-22

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path. When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass. This vulnerability is fixed in 4.12.12.

Affected products

• honojs hono: through 4.12.11

References

• https://github.com/honojs/hono/commit/9aff14bd727f8b0435c963363fd803260e7b8e3c
• https://github.com/honojs/hono/releases/tag/v4.12.12
• https://github.com/honojs/hono/security/advisories/GHSA-wmmm-f939-6g9c

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